Photonic crystals (PCs) with tunability in the visible or near infrared region are of interest for controlling and processing light for active components of display, sensory or telecommunication devices. The position of a stop-band can be modulated either by changing the refractive index and/or the periodicity of the PC structure. Various tunable PCs have been demonstrated and many of these are based on colloidal crystal arrays (CCA). Block copolymers have also been used as a material platform for creating PC structures where self-assembly of high molecular weight block copolymers (BCP) yields 1D, 2D and 3D periodic PC from lamellae, hexagonally packed cylinders and double gyroid microdomain structures. Limited tunability of BCP PC has been accomplished via addition of homopolymers to change the domain spacing with the addition and selective sequestration of nanoparticles for manipulation of the refractive index, resulting in shifts of about 100˜200 nm of the stop band position.
Accordingly, improved methods are needed.